Method of forming a spar layup for an aerodynamic rotor blade

Abstract

A simplified layup mandrel with no contour or twist is utilized by the method of this invention for forming the spar member of an aerodynamic rotor blade. A fiber glass tape is wrapped (laid-up) to a desired thickness onto the simplified mandrel to form a strap as the initial step. Because of the simple design of the mandrel, the laid-up strap when removed from the mandrel has a basic U-shaped configuration with straight extending legs having substantially parallel vertically oriented faces. This strap is then placed on a forming mandrel and contoured to the desired shape either by hand or by coining in a forming die. The contoured strap is then utilized in any of the various subassemblies or final assembly of the composite aerodynamic rotor blade.

What is claimed is: 
     
       1. A method of forming a spar layup for an aerodynamic rotor blade including the steps of: a. laying-up a continuous tape strand onto an elongated mandrel to form a generally U-shaped strap of a given thickness, with leg portions having parallel generally vertically disposed faces;   b. removing the strap from the mandrel;   c. contouring the leg portions of the strap to a desired airfoil portion;   d. repeating steps a-c to form a further generally U-shaped contoured strap; and   e. mounting both straps onto an assembly mandrel to form complementary portions of the spar layup.   
     
     
       2. The method as defined in claim 1, wherein each strap is contoured to the desired airfoil shape by hand on a forming mandrel. 
     
     
       3. The method as defined in claim 1, wherein each strap is contoured to the desired airfoil shape by coining in a forming die. 
     
     
       4. The method as defined in claim 1, further including the steps of: f. surrounding the mandrel on which the strap is formed with a correspondingly U-shaped removable strip against which the continuous tape strand is layed-up;   g. removing the removable strip from the mandrel and formed strap prior to removing the strap.